Cross-compiling libXi

This is the way I got it compiled on LTIB with no error:

./configure –host=arm-linux –enable-malloc0returnsnull

Creating a logo to Linux kernel

The logo format has changed for Linux 2.6.x-kernels, it is
now no longer necessary to use fblogo to include a custom
logo with the kernel.

Thanks to Harald Dunkel
for these instructions:

This is how to replace the fb logo for kernel 2.6.x:

- convert your favourite logo into ppm (ASCII), e.g.

cd /usr/share/doc/fblogo/examples/logo_300×80
pngtopnm debian.png | pnmtoplainpnm >debian224.ppm

- copy the ppm file into your kernel source tree, e.g.

cp -p debian224.ppm
/usr/src/linux-2.6.1/drivers/video/logo/logo_linux_clut224.ppm

- rebuild your kernel

It might be necessary to reduce the number of colors
depending on the target graphics card, e.g.

# pngtopnm debian.png >debian.pnm
# pnmcolormap 16 debian.pnm >colormap16.pnm
pnmcolormap: making histogram…
pnmcolormap: 133 colors found
pnmcolormap: choosing 16 colors…
# pnmremap -map=colormap16.pnm debian.pnm | pnmtoplainpnm >debian16.ppm
pnmremap: 16 colors found in colormap

Source: http://olympus.het.brown.edu/cgi-bin/dwww?type=file&location=/usr/share/doc/fblogo/README-2.6

Linux Network HowTo

It is a little old, but still helpful:

http://d.scribd.com/docs/2pedo2m7a8748qgdz8i.pdf

WoW! My ICQ still alive

I can’t believe it: my ICQ still working!

I got my ICQ# 190580 (yes, it is my birthday) more than 10 years ago and I stopped to use it about 6 years ago.

Everything dies, but ICQ will be remembered forever…

Converting image to yuv format

I used ffmpeg to convert images (png, jpg, etc) to yuv (yuv420) in order to use this yuv file as input to theora encoder.

This is the command I used to create the yuv:

ffmpeg -f image2 -i test.png -pix_fmt yuv420p test.yuv

Use ack to search pattern

Normally I use find, xargs and grep to search pattern on source code (besides cscope):

find . -type f | xargs grep pattern

But it is not efficient mainly because it will search on all binary file and it will search on .cvs, .svn, .git directory.

A good alternative it the “ack” program:
http://betterthangrep.com/

On Ubuntu you can just install ack-grep package:
sudo apt-get install ack-grep

Example:

$ ack-grep mxc-mmc
drivers/mmc/host/mxcmmc.c
45:#define DRIVER_NAME "mxc-mmc"

arch/arm/mach-mx3/clock.c
546:    _REGISTER_CLOCK("mxc-mmc.0", NULL, sdhc1_clk)
547:    _REGISTER_CLOCK("mxc-mmc.1", NULL, sdhc2_clk)

arch/arm/mach-mx3/devices.c
274:    .name = "mxc-mmc",
281:    .name = "mxc-mmc",

arch/arm/mach-mx2/devices.c
369:       .name           = "mxc-mmc",
400:       .name           = "mxc-mmc",

arch/arm/mach-mx2/clock_imx27.c
638:    _REGISTER_CLOCK("mxc-mmc.0", NULL, sdhc1_clk)
639:    _REGISTER_CLOCK("mxc-mmc.1", NULL, sdhc2_clk)
640:    _REGISTER_CLOCK("mxc-mmc.2", NULL, sdhc3_clk)

Listing video formats supported by your webcam

Currently I am developing an application to encode webcam video stream directly to Ogg Theora. During my search I found some interesting projects and documentation.

The first one is the linpvr (Linux personal video recorder), this is an interesting project, but it is unfinished, then don’t wait to get it working, but it can be used as example to know how to convert RBG to YUV and to convert YUV to Theora:
http://code.google.com/p/linpvr/source/checkout

Other useful project is Etheora, this is a set of API developed to simplify Theora usage, it have many conversion routines (RGBxyz -> YUV420, etc):
http://wiki.xiph.org/index.php/Etheora

I am planing to use a webcam which supports natively YUV420 since this is the input format used on Theora encoding routines. Using VIDIOC_ENUM_FMT we can list what format the webcam and its kernel driver supports.

You can use this sample code to list your webcam capabilities:
http://blogs.adobe.com/penguin.swf/2008/07/paparazzi_v2_1.html

In that post’s comments we can find a great listing of webcams and their supported formats.

uCFLTK

Today I found something I was looking for long time ago: someone porting FLTK from C++ to C.

It is called uCFLTK mainly focused to microcontrollers (uC) because normally uC doesn’t have C++ compiler available:

http://www.kiwacan.co.nz/fltk/

Currently it is just on initial stage, but I think it is promising idea!

French radio amateur develops triode valves

This French radio amateur is creating triode valves (transistor’s grandfather):

http://paillard.claude.free.fr/

The video is fantastic, this is like an amazing craft art!

I hope we could to develop transistor (and integrated circuits) in future. Some people suggest nanotechnology will let anyone do develop IC themselves, just like creating photography.

can’t open /dev/si: No such file or directory

I was getting this error message when booting OpenEmbedded on i.MX27ADS:

Bad inittab entry at line 5
can't open /dev/si: No such file or directory

Solution:
Just removed “init=/linuxrc” from my kernel command line and all goes fine